As the U.S. braces for winter and flu season, the national COVID-19 vaccination effort is as urgent as it ever has been. Still, many Americans remain hesitant.

According to a recent survey conducted by the U.S. Census Bureau, 26,870,000 Americans — or 10.8% of the 18 and older population — say they will either probably or definitely not agree to receive the vaccination.

The share of Americans who will likely refuse vaccination varies considerably nationwide, from as many as 25.0% of the adult population to as little as 4.2%, depending on the state. States where the largest shares of adults are open to taking the vaccine are concentrated in the Northeast.

Many Americans who have yet to be vaccinated cite one of three reasons: either they are concerned about possible side effects, or they want to wait to see if it is safe, or it is difficult for them to obtain a vaccination. Others cite different reasons.

Nationwide, 17,000,000 people, 6.8% of the adult population, do not trust the COVID-19 vaccines, and another 9,970,000, or 4.0%, do not think COVID-19 is a big threat. Additionally, 15,250,000 American adults, or 6.1% of the 18 and older population, have not been vaccinated because they do not trust the government.

Meanwhile, the virus continues to spread. Since the beginning of the pandemic, there have been 45,968,940 confirmed cases of the virus and a total of 744,398 Americans have died as a result.

So far, 193,832,584 Americans — or 59.2% of the total population — have received the full course of vaccinations necessary to protect against COVID-19.

All survey data used in this story was published by the Census on Oct. 20, 2021. All data related to COVID-19 infections, fatalities, and vaccinations is current as of Nov. 5, 2021.